JP4324008B2 - Electrophotographic equipment - Google Patents

Description

  The present invention relates to an electrophotographic apparatus such as a copying machine, a laser printer, and a fax machine, and an electrophotographic photosensitive member used in the electrophotographic apparatus.

  Conventionally, the following methods are known as methods for stabilizing the image density of image forming apparatuses such as copying machines and printers (see, for example, Patent Documents 1 and 2).

  For example, a method for stabilizing image density by adjusting image processing (image control) is known. Specifically, a specific pattern (patch image) is formed on an image carrier such as a photosensitive drum (hereinafter also referred to as a photoreceptor) after the image forming apparatus is started and the warm-up operation is completed or during the output operation. Then, the density of the formed pattern is read, and γ correction is performed on the basis of the read density value (a γ curve is derived from the relationship between the drum surface potential after exposure and the density of toner formed on the drum, There is a method of stabilizing the quality of an image to be formed by changing the operation of a circuit for determining image forming conditions such as a correction circuit for adjusting to an appropriate color gradation.

  Further, when the image forming apparatus is used for a long period of time, there may occur a case where the density obtained by reading the pattern on the image carrier does not match the density of the actually printed image. For this reason, a method is also known in which a specific pattern is formed on a recording material and the image forming conditions are corrected by the density value.

  Furthermore, as a method for adjusting the toner density in the developing device, a method of replenishing toner by a method of detecting and controlling the amount of reflected light from the developer (developer reflection ATR) is known. Specifically, the toner excess / shortage amount required to return the patch image density to the initial density is calculated from the output signal of the density difference of the specific pattern (patch image) on the image carrier, and the toner replenishment amount is calculated as the developer. There is known a method of stabilizing the image density by adding and subtracting to and correcting the target value set in the reflection ATR and supplying the corrected toner supply amount.

There are two types of sensors that form the specific pattern (patch image) on an image carrier such as a photosensitive drum and read the density of the formed pattern. One is a scattering type optical density sensor mainly used for toner density control, and the other is a regular reflection type optical density sensor mainly used for γLUT correction.

  The scattering type optical density sensor is a type of sensor that detects the patch density by increasing or decreasing the amount of scattered light from the toner and the image carrier. In the case of a color image forming apparatus, the reflectance with respect to the projected light is a color toner, Since the photosensitive drum and black toner are higher in order, the sensor output increases when the amount of color toner on the photosensitive drum increases, and the density is detected by decreasing the sensor output when the amount of black toner increases. A sensor that determines the density by increasing or decreasing the scattered light can be referred to as a scattering-type optical density light sensor even if it has a configuration in which specularly reflected light enters the sensor light receiving unit.

  On the other hand, the specular reflection type optical density sensor is a type of sensor that detects the patch density by increasing or decreasing the amount of specularly reflected light from the image carrier, and a toner that scatters projection light on a mirror-like photosensitive drum. The sensor output decreases and the patch density is detected. As long as the sensor determines the density based on the increase / decrease of the specular reflection light, it can be said to be a specular reflection type optical density sensor even if the scattered light enters the sensor light receiving unit.

  By the way, as an electrophotographic photosensitive member used in an electrophotographic apparatus, a photosensitive member using an organic material is widely used because of advantages such as low cost and productivity. As the organic photoreceptor, a function-separated photoreceptor in which a charge generation layer containing an organic photoconductive dye or pigment and a charge transport layer containing a photoconductive polymer or a low molecular organic photoconductive material are laminated is the mainstream. When the charge transport layer is a surface layer, the layer has a structure of a molecular dispersion polymer in which an organic photoconductive substance is dispersed in a polymer, and therefore its mechanical strength depends on the polymer. With the high image quality and long life, the durability was not sufficient.

  On the other hand, it is known that it is effective to use a curable resin for the surface layer in order to increase the durability of the photoreceptor (for example, Patent Documents 3, 4, and 5).

  When a curable resin is used for the surface layer of the photoreceptor, mechanical strength is increased, it is difficult to scrape, scratches are less likely to occur, and the life is longer than a thermoplastic resin or the like. Further, when a curable resin is used for the surface layer of the photoreceptor, it is also known that it is useful to use an electron beam as a curing means from the viewpoint of durability against scratches and abrasions on the surface layer. (For example, refer to Patent Document 4).

  When the electrophotographic photoreceptor is continuously used (also referred to as durability use or durability in this specification), the surface of the photoreceptor is subjected to electrical and mechanical stress. The surface roughness value changes every moment. In this case, the sensor output value when the specular reflection type optical density sensor used for γLUT correction is affected by the surface roughness of the photoconductor, the ratio of error to the measured value increases with durability. In particular, when only a small amount of toner is present on the photosensitive drum, it is greatly affected by the surface roughness of the photosensitive member, so that the influence on the γ correction at the low density portion of the toner becomes large and the error becomes more problematic.

  On the other hand, a photoconductor using the above curable resin with high durability is effective in suppressing the generation and growth of scratches caused by durability, but the generation and growth of scratches are not a little. Therefore, even if such a photoconductor is used, if it is used for a long period of time, the output value of the regular reflection type optical density sensor will fluctuate greatly, and the toner density cannot be accurately grasped, resulting in stable gradation. An image with excellent characteristics cannot be output.

  A method for determining the toner density from the system aspect of the electrophotographic apparatus is also conceivable. For example, assuming the surface roughness value of the photoreceptor with respect to the number of durable sheets, a toner correction coefficient value is calculated from the estimated value, and this correction coefficient value is fed back to the density value detected during the durability, and the true value is calculated. A method of obtaining a toner density value is conceivable. However, with this method, it is not possible to set an appropriate correction coefficient value for the surface roughness value of the photoreceptor that changes in various usage situations. In other words, because the surface roughness value of the photoconductor changes greatly due to disturbances such as paper type and environmental differences, the toner density cannot be uniquely determined only by the correction coefficient value for the number of durable sheets. Satisfactory correction coefficient values could not be calculated for a wide range of users used below, and accurate toner density could not be grasped.

JP 2003-195583 A JP 2003-091111 A Japanese Patent Laid-Open No. 07-72640 JP 2000-66425 A Japanese Patent Laid-Open No. 08-272197

The present invention has been made under such circumstances, and a regular reflection toner density detection means for detecting the toner density on the electrophotographic photosensitive member, and the toner density obtained from the regular reflection toner density detection means. An electrophotographic apparatus having an image density control means for controlling an image density according to information, wherein the toner density can be detected with high accuracy and high stability over a long period of time, and the gradation stability is improved. It is an object of the present invention to provide an electrophotographic apparatus that can continue to output excellent images even after endurance.

  Therefore, as a result of intensive studies, the present inventors have not significantly changed the surface roughness of the photoreceptor even after the endurance, and perform the toner density detection using the regular reflection type optical sensor well after the endurance. It has been found that an electrophotographic apparatus having such a photoreceptor can solve the above problems by finding the structure of the photoreceptor that can be used, and has completed the present invention.

That is, the present invention is as follows.
(1) detects an electrophotographic photosensitive member which is rotationally driven, a charging unit, an exposing unit, a developing unit, the toner density on the electrophotographic photosensitive member after extent development Engineering by developing means An electrophotographic apparatus comprising: a regular reflection toner density detection means for controlling the image density according to toner density information obtained from the regular reflection toner density detection means;
The surface layer of the electrophotographic photosensitive member contains a compound cured by polymerizing or crosslinking a compound having two or more polymerizable functional groups by electron beam irradiation ,
The surface of the electrophotographic photosensitive member is roughened by roughening means for roughening the surface of the electrophotographic photosensitive member by rotating the electrophotographic photosensitive member by constantly pressing the polishing sheet against the surface of the electrophotographic photosensitive member. , Grooves having a width of 0.5 to 40 μm are formed at a ratio of 20 to 1000 per unit area (/ mm ² ) ,
An electrophotographic apparatus, wherein a groove having a width larger than 40 m is not formed on the surface of the electrophotographic photosensitive member .

  According to the present invention, an electrophotographic apparatus capable of detecting toner density for a long period of time with high accuracy and high stability, and outputs a high-definition image having excellent gradation stability even after endurance. An electrophotographic apparatus that can continue can be provided.

Hereinafter, the present invention will be described in detail.
The electrophotographic apparatus of the present invention includes at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, a regular reflection toner concentration detecting unit for detecting the toner concentration on the electrophotographic photosensitive member, and the positive unit. The image density control means for controlling the image density based on the toner density information obtained from the reflection toner density detection means, and the regular reflection toner density detection means is a toner on the electrophotographic photosensitive member after the developing process. The surface layer of the electrophotographic photosensitive member contains a compound cured by polymerizing or crosslinking a compound having a polymerizable functional group, and the electrophotographic photosensitive member has a surface layer. on the surface, being formed at a ratio of the groove is formed, and grooves unit area of the width of the groove is 0.5~40μm (/ mm ²⁾ per 20 to 1,000 by roughening means A.

  In general, when the surface layer of the photoreceptor is a layer formed by curing a compound having a polymerizable functional group, it is more resistant to scraping and scratches than a layer formed of a thermoplastic resin, before and after durability. The fluctuation range of the surface roughness state of the photoreceptor can be reduced. If the density of toner is detected by a regular reflection type optical density sensor using such a photoconductor, it can be expected to some extent that the influence of the error can be reduced. However, an object of the present invention is to provide an electrophotographic apparatus capable of continuously outputting a high-definition image with high stability even after endurance. Here, the high-definition image means that the gradation of the low density portion is output as prescribed, and the high stability means that the high-definition image continues to be output without changing for a long period of time. means. In order to achieve such an object, it cannot be said that a photoreceptor having a surface layer formed by curing the compound having a polymerizable functional group is sufficient. In particular, it has not been possible to provide a satisfactory electrophotographic apparatus in terms of continuously outputting a good image with high stability.

  By the way, a surface layer formed by curing a compound having a polymerizable functional group is further formed with a specific groove width at a specific ratio by a roughening means, and a photoreceptor having such a surface layer is obtained. When used, the fluctuation range of the surface roughness state of the photoreceptor before and after the endurance can be reduced, and the fluctuation of the output value of the regular reflection type optical density sensor can be reduced, and the toner density after the endurance can be detected. It was confirmed that the process can be performed well. Therefore, when such a photoconductor is used, an electrophotographic apparatus that continues to output a good image with high stability can be provided.

In the present invention, the width of the groove formed in the surface layer is preferably 40 μm or less so as not to be recognized as a scratch on the display screen.
If a groove having a groove width larger than 40 μm is formed in the initial state of the surface of the photoreceptor, many deep scratches are generated on the surface after the endurance. This is because if the groove width is too wide, particles in the shape of the groove stay in the groove in the electrophotographic process, and it grows in the depth direction and width direction of the groove by being pressed with a cleaning blade or the like. However, it is thought that it becomes a wound. This affects the detection result of the toner density using the regular reflection type optical sensor.

In the present invention, the grooves formed in the surface layer are formed with a groove width of 0.5 to 40 μm at a rate of 20 to 1000 per unit area (/ mm ² ).
Here, when the groove density of the groove width of 0.5 to 40 μm is less than 20, the frictional force generated between the electrophotographic system and a contact member such as a cleaning blade on the surface of the photoreceptor is very large. turn into. That is, the contact member is pressed against the photoconductor with high pressure. When endurance is performed in this state, when foreign matter such as lint mixed in the main body is sandwiched between the contact member and the photosensitive member, they are strongly pressed against the photosensitive member, and at the initial stage of durability, It becomes a deep groove. The groove condition once stabilizes in the middle durability period, but the rough surface of the photoreceptor surface changes greatly from the initial stage due to the deep groove in the initial stage of durability and the growth of the groove in the middle to long term. However, the fluctuation range before and after the endurance increases. As a result, when the post-durability toner density is detected using a regular reflection type optical sensor, it is adversely affected and a high-definition image cannot be output with high stability.

  In addition, even if the width of the groove is within 40 μm, when the surface roughness value (Rz value) is less than 0.3 μm, it was confirmed that the same phenomenon as described above is likely to occur, so the Rz value is It is good that it is 0.3 μm or more.

In addition, when the groove density with a groove width of 0.5 to 40 μm is larger than 1000, the frictional force can be reduced, which is advantageous, but the distance between the grooves is narrow, and the grooves are durable. As a result, it is easy to bond, and a large amount of one groove width exceeding 40 μm is formed on the surface of the photoreceptor. In this case, as described above, particles in the form of particles stay in the groove, and when they are pressed by a cleaning blade or the like, they grow in the depth direction and width direction of the groove and become scratches. Therefore, the value of the specular reflection type optical density detection is affected, and as a result, a high-definition image cannot be output with high stability after durable use. In addition, in a system using a scattering type optical density sensor, if the grooves are dense, scattering on the surface of the photoreceptor increases, the amount of reflected light returning to the sensor is too small, and the S / N is reduced. The problem that detection becomes difficult also arises. Further, since optical scattering occurs on the surface, another adverse effect that the latent image is disturbed when the latent image is formed by the laser is also exhibited. Therefore, the groove density with a groove width of 0.5 to 40 μm is preferably 1000 or less.

  When the Rz value is larger than 1.3 μm from the beginning, the growth rate of the groove proceeds relatively fast, and when used for a long time, the groove becomes thicker in the width direction and deeper in the depth direction. In this case as well, the surface roughness of the surface of the photoconductor changes greatly from the beginning, affecting the value of the specular reflection type optical density detection, and it becomes impossible to output a high-definition image with high stability after durable use. End up. Therefore, the Rz value is preferably 1.3 μm or less.

  Further, when the groove formed on the surface layer of the photoreceptor is not in a uniform rough surface state and the value of the maximum surface roughness (Rmax) −Rz is larger than 0.3, the groove depth However, since the growth rate of the grooves is different, the difference in depth and width of each groove increases as durability increases, and as the durability is used, scattering increases and the above-mentioned problems occur. It becomes easy. Therefore, the value of Rmax−Rz is preferably 0.3 or less.

In the present invention, the measurement of groove density, groove width, Rz, and Rmax can be performed according to the method described in the examples described later. However, although the measurement method using the micromap is described in the examples, in addition to the method using the micromap measuring machine, for example, for the surface observation, a commercially available laser microscope (ultra-deep shape measurement microscope VK-8550) is used. , VK-9000 (manufactured by Keyence), scanning confocal laser microscope OLS3000 (manufactured by Olympus) Real Color Confocal Microscope Oplitex C130 (manufactured by Lasertec)), digital microscope (VHX-100, VH-8000 (Keyence) It is also possible to use, for example, WinROOF (manufactured by Mitani Trading Co., Ltd.) as image processing software, and obtain the groove width and number of grooves. Using a shape measuring device (NewView 5032 (manufactured by Zygo)) etc. It is also possible to measure.

The surface layer in the present invention will be described in detail below.
The surface layer of the present invention is formed by curing a compound having a polymerizable functional group. As the curing means, heat, visible light, light such as ultraviolet rays, and radiation (electron beam, γ-ray, etc.) can be used. In order to find the effect of the present invention more remarkably, the surface layer is preferably cured with an electron beam. This is because, by irradiating a high-energy electron beam for a short time and curing the surface layer, the electrical characteristics (for example, increase in residual potential) on the electrophotographic characteristics are not impaired, This is because a desired groove shape can be formed in the present invention.

The procedure for forming the surface layer in the present invention is as follows.
A coating solution that dissolves or contains a compound for the surface layer that can be cured by polymerization or crosslinking is applied by a dip coating method, a spray coating method, a curtain coating method, a spin coating method, etc. To cure. The dip coating method is more preferable for efficient mass production of the photoreceptor.

The structure of the photoconductor of the present invention is a single layer type in which both a charge generation material and a charge transport material are contained in the same layer on a conductive substrate, or a charge generation layer containing a charge generation material and a charge transport. Any of a stacked type in which the charge transport layers containing substances are stacked in this order or in the reverse order may be used. Furthermore, a surface protective layer can be formed on the photosensitive layer. In the present invention, at least the surface layer of the photoreceptor only needs to contain a compound that can be polymerized or crosslinked and cured by heat, light such as visible light or ultraviolet light, and radiation. However, from the viewpoint of characteristics as a photoreceptor, in particular, electrical characteristics such as residual potential and durability, a configuration of a function-separated type photoreceptor in which a charge generation layer / charge transport layer are laminated in this order, or laminated in this configuration. It is preferable that a surface protective layer is formed on the photosensitive layer.

  In the present invention, the surface layer polymerization or the curing method of the compound to be cross-linked does not cause an increase in the residual potential without deterioration of the characteristics of the photoconductor, and the fluctuation range of the surface roughness of the photoconductor in durability can be made smaller and more effective. Therefore, it is preferable to use an electron beam as described above.

  In the case of electron beam irradiation, any type of accelerator such as a scanning type, an electro curtain type, a broad beam type, a pulse type, and a laminar type can be used. In the case of irradiating an electron beam, the acceleration voltage is preferably 250 KV or less, and optimally 150 KV or less, in order to develop the electrical characteristics and durability performance of the photoreceptor of the present invention. The irradiation dose is preferably in the range of 1 Mrad to 100 Mrad, more preferably in the range of 3 Mrad to 50 Mrad. If the accelerating voltage exceeds the above, the electron beam irradiation damage tends to increase on the characteristics of the photoreceptor. Further, when the irradiation dose is less than the above range, the curing tends to be insufficient, and when the dose is high, the photoreceptor characteristics are easily deteriorated.

  Surface layer compounds that can be polymerized or crosslinked and cured include unsaturated polymerizable functional groups in the molecule in terms of high reactivity, high reaction rate, and high hardness achieved after curing. Those having a group are preferred, and among them, compounds having an acrylic group, a methacryl group, and a styrene group are particularly preferred.

  In the present invention, the compound having an unsaturated polymerizable functional group is roughly classified into a monomer and an oligomer by repeating the structural unit. The monomer means that the structural unit having an unsaturated polymerizable functional group is not repeated, and indicates a relatively small molecular weight, and the oligomer is a structural unit having an unsaturated polymerizable functional group having about 2 to 20 repeating units. A polymer is shown. Also, a macromer having an unsaturated polymerizable functional group only at the terminal of the polymer or oligomer can be used as the curable compound for the surface layer of the present invention. Among them, in the present invention, it is preferable to use a compound having at least two polymerizable functional groups.

  Further, the compound having an unsaturated polymerizable functional group in the present invention is more preferably a charge transport compound in order to satisfy a charge transport function necessary for the surface layer. Among these, an unsaturated polymerizable compound having a hole transport function is more preferable.

  Although the example of the compound which has an unsaturated polymerizable functional group in this invention is shown in Table 1 and Table 2, it is not limited to these compounds.

Next, the photosensitive layer of the electrophotographic photoreceptor in the present invention will be described in detail.
The support for the electrophotographic photosensitive member may have any conductivity, for example, a metal or alloy such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or sheet, aluminum and copper Metal foil such as laminated on plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, metal with conductive layer applied alone or with binder resin, plastic Examples include film and paper.
In the present invention, an undercoat layer (hereinafter also referred to as an intermediate layer) having a barrier function and an adhesive function can be provided on the conductive support.

  The undercoat layer is used to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, and protect the photosensitive layer from electrical breakdown. Formed.

  Materials for the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, N-methoxymethylated 6 nylon, copolymer nylon, glue and gelatin Etc. can be used. These are dissolved in a solvent suitable for each and coated on a support. The film thickness at that time is preferably 0.1 to 2 μm.

  When the photoreceptor of the present invention is a function separation type photoreceptor, a charge generation layer and a charge transport layer are laminated. Examples of the charge generation material used in the charge generation layer include selenium-tellurium, pyrylium, thiapyrylium dyes, various central metals and crystal systems, specifically, crystal types such as α, β, γ, ε, and X types. Phthalocyanine-based compounds, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, monoazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine pigments, quinocyanines, and JP-A No. 54-143645 Examples include amorphous silicone.

  In the case of a function-separated type photoreceptor, the charge generation layer includes the above charge generation material in a 0.3 to 4 times amount of binder resin and solvent, such as a homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor and roll mill. The dispersion is well dispersed by a method, and the dispersion is applied and dried, or formed as a single composition film such as a vapor deposition film of the charge generation material. The film thickness is preferably 5 μm or less, and particularly preferably in the range of 0.1 to 2 μm.

  When the binder resin is used, the binder resin includes polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, trifluoroethylene, polyvinyl Examples include alcohol, polyvinyl acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, and epoxy resin.

  When an unsaturated polymerizable compound having a hole transport function as described above is used as the charge transport material used in the charge transport layer, the layer having the compound is used as a charge transport layer on the charge generation layer. Alternatively, it can be formed as a surface protective layer after forming a charge transport layer comprising a charge transport material and a binder resin on the charge generation layer.

When the layer having an unsaturated polymerizable compound having the hole transport function is used as a surface protective layer, the charge transport layer corresponding to the lower layer is formed of an appropriate charge transport material such as poly-N-vinylcarbazole, poly Polymer compounds having a heterocyclic ring or condensed polycyclic aromatics such as styryl anthracene, heterocyclic compounds such as pyrazoline, imidazole, oxazole, triazole, carbazole, triarylalkane derivatives such as triphenylmethane, and triarylamines such as triphenylamine A low molecular weight compound such as a reelamine derivative, a phenylenediamine derivative, an N-phenylcarbazole derivative, a stilbene derivative, or a hydrazone derivative is used as an appropriate binder resin (similar to the binder resin described above for the charge generation layer). Can be used) and dispersed / dissolved in solvent Applied by a known method described above can be formed by drying. In this case, the ratio of the charge transport material to the binder resin is preferably selected in the range of 30 to 100, preferably 50 to 100, when the total weight of both is 100. If the amount of the charge transport material is less than that, the charge transport ability is lowered, and problems such as a decrease in sensitivity and an increase in residual potential occur. Also in this case, the thickness of the photosensitive layer is in the range of 5 to 30 μm, and the thickness of the photosensitive layer at this time is the total thickness of the charge generation layer, the charge transport layer, and the surface protective layer. .

  In any case, the surface layer is generally formed by applying a solution containing the compound having an unsaturated polymerizable functional group, followed by a polymerization / curing reaction. It is also possible to form the surface layer by using a solution obtained by reacting a solution containing a group-containing compound to obtain a cured product and then again dispersing or dissolving it in a solvent. Examples of the method for applying these solutions include the dip coating method, the spray coating method, the curtain coating method, and the spin coating method as described in the explanation of the surface layer. Of these methods, the dip coating method is more preferable from the viewpoint of efficiency / productivity. Moreover, vapor deposition, plasma, and other known film forming methods can be appropriately selected.

Conductive particles may be mixed in the surface protective layer in the present invention.
Examples of the conductive particles include metals, metal oxides, and carbon black. Examples of the metal include aluminum, zinc, copper, chromium, nickel, stainless steel, and silver, or those obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide, and antimony-doped zirconium oxide. These can be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion.

The average particle size of the conductive particles used in the present invention is preferably 0.3 μm or less, and particularly preferably 0.1 μm or less, from the viewpoint of the transparency of the protective layer.
In the present invention, among the conductive particles as described above, it is particularly preferable to use a metal oxide in terms of transparency.

The ratio of the conductive metal oxide particles in the surface protective layer is one of the factors that directly determine the resistance of the surface protective layer, and the resistance of the protective layer is in the range of 10 ¹⁰ to 10 ¹⁵ ohm · cm. It is preferable.

The surface layer in the present invention can contain fluorine atom-containing resin particles.
Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and their co-polymers. One or two or more types are preferably selected from the combination, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable. The molecular weight of the resin particles and the particle size of the particles can be appropriately selected and are not particularly limited.

  The proportion of fluorine atom-containing resin particles in the surface layer is preferably 5 to 70% by weight, more preferably 10 to 60% by weight, based on the total weight of the surface layer. If the proportion of fluorine atom-containing resin particles is more than 70% by weight, the mechanical strength of the surface layer tends to decrease, and if the proportion of fluorine atom-containing resin particles is less than 5% by weight, the surface layer surface releasability, surface layer In some cases, the wear resistance and scratch resistance are not sufficient.

  In the present invention, additives such as radical scavengers and antioxidants may be added to the surface layer for the purpose of further improving dispersibility, binding properties and weather resistance.

  The film thickness of the surface protective layer used in the present invention is preferably in the range of 0.2 to 10 μm, more preferably in the range of 0.5 to 6 μm.

On the surface of the electrophotographic photosensitive member in the present invention, grooves having a groove width of 0.5 to 40 μm are formed at a ratio of 20 to 1000 per unit area (/ mm ² ) by the following roughening means. Yes.

  Note that the roughening means that can form a roughened surface satisfying the above range is not limited to the following method.

  FIG. 3 shows an example of roughening means having a roughening mechanism using a polishing sheet, which is used for manufacturing an electrophotographic photosensitive member incorporated in the electrophotographic apparatus of the present invention. The abrasive sheet is a sheet in which abrasive grains are dispersed in a binder resin and applied to a substrate. The polishing sheet 3-1 is wound around a hollow shaft 3-a, and a motor (not shown) is disposed in a direction opposite to the direction in which the sheet is fed to the shaft 3-a so that tension is applied to the polishing sheet 3-1. ing. The polishing sheet 3-1 is fed in the direction of the arrow, passes through the backup roller 3-3 via the guide rollers 3-2 (1) and 3-2 (2), and the polished sheet is the guide roller 3-2 (3 ) Is wound around the winding means 3-5 by a motor (not shown) via 3-2 (4). The polishing is basically performed by constantly pressing an untreated polishing sheet against the surface of the photoconductor to roughen the surface of the photoconductor. The part in contact with the polishing sheet 3-1 is grounded to the ground or has conductivity.

  The feed speed of the polishing sheet is preferably in the range of 10 to 500 mm / sec. If the feed amount is small, the polishing sheet polished on the surface of the photoconductor will come into contact with the surface of the photoconductor again, resulting in the formation of deep grooves on the surface of the photoconductor, uneven surface grooves, and adhesion of binder resin on the surface of the polishing sheet. It may occur and is not preferable.

  The electrophotographic photoreceptor 3-4 is placed at a position facing the backup roller 3-3 through the polishing sheet 3-1. At this time, the backup roller is pressed against the backup roller 3-3 with a desired set value from the base material side of the polishing sheet 3-1, and the surface of the photoreceptor is roughened. The rotation direction of the electrophotographic photosensitive member may be the same as, or opposite to, the direction in which the polishing sheet 3-1 is fed, or the rotation direction may be changed during polishing.

The pressing pressure of the backup roller against the electrophotographic photosensitive member is determined by the type and particle size (= count) of the abrasive grains of the abrasive sheet, the base material of the abrasive sheet, the binder resin thickness of the abrasive grains and the sheet, The optimum value differs depending on the hardness and the hardness of the surface layer constituting the surface of the photoreceptor, but 0.005
If it is in the range of ˜1.5 N / m ² , the groove shape on the surface of the photoreceptor in the present invention is achieved. The groove shape (groove width, groove density, surface roughness, etc.) on the surface of the photoreceptor in the present invention is determined by the polishing sheet feed speed, the pressing pressure of the pack-up roller, the abrasive grain size, shape, and polishing sheet. It can be adjusted by appropriately selecting the count, the binder resin thickness of the polishing sheet, the substrate thickness, and the like.

As abrasive grains, aluminum oxide, chromium oxide, silicon carbide, diamond, iron oxide, diamond, cerium oxide, corundum, silica, silicon nitride, boron nitride, molybdenum carbide, silicon carbide, tungsten carbide, titanium carbide, silicon oxide Etc. The average particle diameter of the abrasive grains (the average particle diameter of the median particle diameter (median diameter D50) by centrifugal sedimentation method) is 0.01 to 50 μm, more preferably 1 to 15 μm. If the particle size is too small, the depth and width of the groove considered to be suitable for the present invention cannot be obtained, and if it is too large, the difference between Rmax and Rz becomes large, unevenness on the halftone image, grooves appear in the image, etc. There is a tendency to cause defects.

  The abrasive grains of the abrasive sheet are applied by dispersing abrasive grains in a binder resin on a substrate. The abrasive grains in the binder resin are preferably dispersed with a particle size distribution, but the particle size distribution may be controlled. For example, even if the average particle size is the same, the numerical value of Rmax−Rz ≦ 0.3 can be further reduced by removing particles on the large particle size side. As another object, it is possible to suppress variations in the average particle diameter during production of the sheet, and as a result, it is possible to suppress variations in the surface roughness: Rz on the surface of the photoreceptor in the present invention.

  The abrasive sheet count correlates with the grain size of the abrasive grains, and the smaller the count number, the larger the average grain diameter of the abrasive grains. Will be put out. In the present invention, the range of the abrasive sheet count is preferably 500 to 20000, more preferably 1000 to 3000.

  In the present invention, the polishing step can be performed a plurality of times so as to obtain a desired groove-shaped photoreceptor surface. In that case, it may be performed from either a coarse sheet to a fine sheet, or vice versa. In the former case, finer grooves can be superimposed on the surface of the rough groove on the surface of the photoconductor, and in the latter case, unevenness of the polishing grooves can be reduced.

  Moreover, you may grind | polish with the grinding | polishing sheet from which an abrasive grain differs even if the number of counts is equal. Since the hardness of the abrasive grains is different, the groove shape on the surface of the photoreceptor required by the present invention may be further optimized. Examples of the binder resin used for the polishing sheet include known thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, ultraviolet curable resins, visible light curable resins, and antifungal resins. Examples of the thermoplastic resin include vinyl chloride resin, polyamide resin, polyester resin, polycarbonate resin, amino resin, styrene butadiene copolymer, urethane elastomer, and nylon-silicon resin. Examples of the thermosetting resin include phenol resin, phenoxy resin, epoxy resin, polyurethane resin, polyester resin, silicon resin, melamine resin, and alkyd resin. The binder resin thickness of the abrasive grain sheet is preferably 1 to 100 μm.

  Examples of the base material used for the polishing sheet include polyester resin, polyolefin resin, cellulose resin, vinyl resin, polycarbonate resin, polyimide resin, polyamide resin, polysulfone resin, polyphenylsulfone resin, and the like.

  The substrate thickness of the polishing sheet is preferably 10 to 150 μm, more preferably 15 to 100 μm.

  The backup roller 3-3 is an effective means for forming a desired groove on the surface of the photoreceptor. Although it is possible to polish only with the tension of the polishing sheet 3-1, the method of forming grooves on the surface of the photoreceptor only with the tension of the polishing sheet 3-1 without using the backup roller 33 has a small number of polishing sheets. It is effective for a thing with a large abrasive grain (300 to 800).

  FIG. 4 shows an example of polishing the surface of the electrophotographic photosensitive member only with the tension of the polishing sheet 3-1. The difference from FIG. 3 is that there is no backup roller 3-3, and the shape of the groove formed on the surface of the electrophotographic photosensitive member 3-4 is mainly controlled by the count of the polishing sheet 3-1, the electrophotographic photosensitive of the polishing sheet. It is determined by the pressure applied to the body 3-4, the polishing time, and the like.

Since the surface layer of the electrophotographic photoreceptor of the present invention contains a compound cured by polymerizing or cross-linking a compound having a polymerizable functional group, the surface has high hardness and the tension of the polishing sheet. In order to create the groove shape of the present invention, a backup roller is used because the pressure on the surface of the photoreceptor alone is low and it is difficult to produce a desired surface state even in combination with a large abrasive particle. Is preferred.

  Examples of the material of the backup roller 3-3 used in the polishing machine include metals and resins. In the step of roughening the surface of the photoreceptor of the electrophotographic photoreceptor, the surface of the photoreceptor is affected by the cylinder runout of the electrophotographic photoreceptor, the cylinder runout of the backup roller 3-3, the polishing pressure distribution in the thrust direction of the polishing sheet 3-1. In view of absorbing these, the material of the backup roller 3-3 is preferably a resin. Further, considering that absorbing unevenness is the first, a foamable resin is more preferable, and considering that the surface of the photoreceptor and the polishing sheet are basically insulating, the material of the backup roller 3-3 is conductive. What has property is more preferable.

  However, although it has electrical conductivity, there is no electrical conductivity between the surface of the polishing sheet 3-1 and the surface of the photosensitive member, so that the polishing sheet 3-1 and the surface of the photosensitive member are charged a little during polishing. Depending on the resistance, etc., the charging voltage is different, but a high voltage may be charged up to several KV. For this reason, it is possible to spray static electricity, electrostatic air or the like on the surface of the photoreceptor, the polishing sheet, and the nip portion thereof during the roughening step.

  When foaming resin is used for the backup roller, if its hardness is low, the backup roller is deformed even if the pressing pressure against the electrophotographic photosensitive member is increased, and the groove width, groove depth, groove within the scope of the present invention The density is not formed. Therefore, in the case of a foamable resin, the lower limit of the hardness is preferably 10 or more in Asker C hardness (measured by Elaston rubber hardness meter ESC type (SRIS0101 / Type C)). On the other hand, the upper limit is preferably 70 or less in order to satisfy the groove density, groove width, and Rmax−Rz ≦ 0.3. More preferable hardness of the backup roller is 15 to 65, and further 25 to 60.

  When foamable resin is used for the backup roller, foreign matter tends to accumulate in the foamable resin hole, so it is necessary to be careful not to allow foreign matter to enter the interface between the polishing sheet and the backup roller. In some cases, it may be effective to blow air or the like on the roller at all times. As the material of the backup roller, in addition to the foamable resin, Shore A hardness (measured by Elaston Rubber Hardness Tester ESA type (JIS 6253 / ISO7619 Type A)) is 5-70, more preferably 10-40. As long as it is a resin, the groove shape on the surface of the photoreceptor specified in the present invention can be formed even in ordinary resins (polyurethane, polystyrene, polypropylene, polycarbonate, polyolefin, fluorine rubber, phenol resin, etc.).

  As shown in FIG. 5, the polishing sheet has a configuration in which a binder resin 3-7 for fixing the abrasive grains 3-8 to the base material 3-6 is applied onto the base material 3-6 of the polishing sheet. is there.

  Next, the electrophotographic apparatus of the present invention for forming an image will be described. FIG. 1 shows an example of the electrophotographic apparatus of the present invention, but the present invention is not limited to this.

  In addition to the above-described electrophotographic photosensitive member, the electrophotographic apparatus of the present invention includes at least a charging unit, an exposing unit, a developing unit, a transfer unit, and a regular reflection toner density detection for detecting the toner density on the electrophotographic photosensitive member. And image density control means for controlling the image density based on the toner density information obtained from the regular reflection toner density detecting means. In the present invention, the regular reflection toner density detecting means is used for detecting the toner density on the electrophotographic photosensitive member after the developing process.

More specifically, as shown in FIG. 1, the printer unit A and an image reading unit (image scanner) B mounted on the printer unit A are provided.

  The printer unit A includes a photosensitive member 1 that is an image carrier, a primary charger 2 that is a charging unit for charging the photosensitive member 1, and light that is applied to the charged photosensitive member 1 according to image information. An exposure device 3 that is an exposure means for forming an electrostatic latent image; a developing device 4 that is a development means for developing the electrostatic latent image formed on the photoreceptor 1 with toner; A transfer body 5 that is a transfer means for transferring a toner image carried by the photoreceptor 1 to the transfer material P, and a cleaning device that removes deposits on the surface of the photoreceptor 1 to which the toner image has been transferred from the surface of the photoreceptor 1. 6, a pre-exposure lamp 7 that erases the electrostatic history by irradiating light on the surface of the photoreceptor 1 from which deposits have been removed, and a transport belt that transports the transfer material P onto which the toner image has been transferred from the transfer body 5. 8 and the toner image of the transfer material P transported by the transport belt 8 is fixed on the transfer material P. And a fixing device 9 to be. Further, as will be described later, the electrophotographic apparatus of FIG. 1 includes the optical density detecting means shown in FIG. 2 and the image control means for controlling the image density based on the toner density information obtained from the optical density means. It is.

  As the photoreceptor 1, for example, an electrophotographic photoreceptor prepared by the method described in the examples is used.

  The primary charger 2 is a corona charger that charges the photoreceptor 1 in a non-contact manner. As the primary charger 2, a contact charger such as a conductive charging roller or a charging brush provided in contact with the photosensitive member 1 can be used.

  For example, as illustrated in FIG. 6, the exposure apparatus 3 includes a light emission signal generator 24 that generates a light emission signal of light to be irradiated based on an image signal read by the image reading unit B, and a light emission signal generator 24. A solid-state laser element 25 that generates laser light in response to a light emission signal, a collimator lens system 26 that defines an optical path width of the generated laser light, a rotary polygon mirror 22 that reflects the laser light having a defined optical path width, And an fθ lens group 23 that causes the photosensitive member 1 to scan the laser beam reflected by the rotary polygon mirror 22.

  The developing device 4 is composed of, for example, a plurality of developing devices and a rotor portion having these in the circumferential portion, and includes a developer having cyan toner, a developer having magenta toner, a developer having yellow toner, and Each developing device that accommodates each developer having black toner is transported to the developing position by the rotation of the rotor portion.

  The developing device is, for example, a two-component developing device as shown in FIG. 7, and a developing container 32 that stores a developer T composed of toner t and a carrier, and a developing device that is rotatably provided in an opening of the developing container 32. The developing sleeve 30 that carries the developer T contained in the container 32, the magnet roller 31 that is fixed inside the developing sleeve 30 and forms a plurality of magnetic poles at a plurality of predetermined positions, and the developing sleeve 30. A regulating blade 33 that regulates the layer thickness of the developer T (for example, a non-magnetic metal plate provided apart from the surface of the developing sleeve 30), a developing chamber R1 on the opening side in the developing container 32, and development A partition wall 36 partitioned into a stirring chamber R2 deeper than the chamber R2, transport screws 37 and 38 for transporting and stirring the developer T in each chamber, and a toner hopper containing toner to be supplied to the stirring chamber R2. A 4, and a supply port 35 of the hopper 34 to open and close toward the stirring chamber R2. The developing sleeve 30 is made of a nonmagnetic material such as aluminum or nonmagnetic stainless copper. The toner t is a color toner containing, for example, a hydrocarbon wax. The developing device can be appropriately selected according to the type of developer used.

The transfer body 5 includes, for example, a roller-shaped transfer sheet 5c that carries the transfer material P, a transfer charger 5a that applies a voltage from the back surface of the transfer material P at the nip portion between the transfer sheet 5c and the photoreceptor 1,
And a separation charger 5b for applying a voltage for separating the transfer material P onto which the toner image is transferred from the transfer sheet 5c.

  The transfer sheet 5c is made of, for example, a polyethylene terephthalate resin film, and is stretched on the surface of the rotating drum, for example. The transfer body 5 is disposed so as to be in contact with and separated from the photoreceptor 1. The transfer body 5 is rotationally driven in the arrow direction (clockwise direction). In the present invention, general materials can be used as the transfer means such as the transfer body 5 and the charger.

  For example, as shown in FIG. 8, the cleaning device 6 adheres to a container-like casing 61 provided so as to open toward the photosensitive member 1 and an outer surface near the upper portion of the opening of the casing 61. A cleaning blade 62 made of urethane rubber or the like provided so as to contact the surface, a brush member 63 provided at a position where the opening of the casing 61 can rotate and slidably rub against the surface of the photoreceptor 1, A scraper 67 that abuts against the brush member 63 and collects the collected matter collected by the brush member 63 from the brush member 63, and a photosensitive member by a cleaning blade 62 provided at the lower end edge of the opening of the casing 61 from the casing 61. The squeeze sheet 64 for preventing the deposits removed from the surface of 1 and the collected matter from falling, and the deposits accommodated in the casing 61 The or collection, etc., and a screw 65 for conveying to the outside of the casing 61.

  The cleaning blade 62 is attached to the opening of the casing 61 by a support member. The cleaning blade 62 abuts one edge in the counter direction with respect to the rotational drive direction (a direction in the figure) of the image carrier 1. Further, the brush member 63 is in contact with the surface of the photoconductor 1 on the upstream side of the cleaning blade 62 in the rotation direction of the photoconductor 1.

  The brush member 63 includes, for example, a rotating shaft and a brush 66 that stands on the surface of the rotating shaft. The rotating shaft is made of metal and is grounded. The brush 66 is formed of conductive fibers. The thickness of the fibers of the brush member 63 is 4 to 30 D / F, and the brush density is 10,000 to 400,000 pieces / square inch.

  The fixing device 9 includes, for example, a fixing roller 9a with a built-in heater, a pressure roller 9b provided to be biased relative to the fixing roller 9a, and a releasability such as silicone oil on the fixing roller 9a. Oil application means for applying oil. The amount of oil applied by the oil applying means is set to a smaller amount than when ordinary toner is used. In the present invention, the oil applying means may not be provided.

  In addition to these, the printer unit A includes a paper feed cassette 10 that accommodates the transfer material P, paper feed rollers 11 and 12 that transport the transfer material P from the paper feed cassette 10 one by one, and toner image transfer. A registration roller 13 that conveys the transfer material P toward the transfer sheet 5 c in accordance with the timing, an adsorption roller 14 that attracts the transfer material P conveyed by the registration roller 13 to the transfer sheet 5 c, and the fixing device 9. A sheet discharge roller 15 for discharging the transfer material P to the outside of the apparatus and a tray 16 for storing the transfer material P discharged to the outside of the apparatus are provided.

  The image reading unit B includes a document table glass 20 on which the document G is placed, and an image reading unit 21 that reads an image of the document G placed on the document table glass 20. The image reading unit 21 includes a document irradiation lamp 21a that illuminates the document G with the document table glass 20 interposed therebetween, a short-focus lens array 21b that collects an image of the document G illuminated by the document irradiation lamp 21a, and a light collecting unit. And a CCD sensor 21c that reads the image of the original G and converts it into an image signal. The CCD sensor 21c is a full color sensor.

  Next, the operation of the electrophotographic apparatus according to the present invention will be described. The electrophotographic apparatus of the present invention can appropriately use known means and apparatuses relating to image formation, and is not limited to this embodiment.

  The photosensitive member 1 is driven to rotate in the direction of arrow a (counterclockwise) at a predetermined peripheral speed (process speed) around the central support shaft, and in the rotation process, the photosensitive member 1 is negatively charged in the present embodiment by the primary charger 2. A uniform corona charging process.

  Then, a laser beam modulated in response to an image signal output from the image reading unit B to the printer unit A side, which is output from the exposure device (laser scanning device) 3 to the uniformly charged surface of the photoreceptor 1. As a result of scanning exposure L, an electrostatic latent image of each color corresponding to the image information of the document G photoelectrically read by the image reading unit B is sequentially formed on the photoreceptor 1.

  The formation of the electrostatic latent image will be described. In the image reading unit B, the original G is placed on the upper surface of the original platen glass 20 with the surface to be copied facing down, and a not-shown original plate is placed thereon. Set. When the copy button (not shown) is pressed, the image reading unit 21 is moved from the home position on the left side to the right side of the platen glass 20 in FIG. Driven forward along the lower surface of the glass, when it reaches a predetermined reciprocating end point, it is driven backward and returned to the initial home position.

  In the forward driving process of the image reading unit 21, the downward image surface of the set original G on the platen glass 20 is sequentially illuminated and scanned from the left side to the right side by the document irradiation lamp 21a. The document surface reflected light is imaged and incident on the CCD sensor 21c by the short focus lens array 21b.

  The CCD sensor 21c includes a light receiving unit, a transfer unit, and an output unit (not shown). In the light receiving unit, an optical signal is changed to a charge signal and is sequentially transferred to the output unit in synchronization with a clock pulse. In the output section, the charge signal is converted into a voltage signal, amplified and reduced in impedance, and output. The analog signal thus obtained is converted into a digital signal by well-known image processing and output to the printer unit A. That is, the image information of the original G is photoelectrically read as a time-series electric digital pixel signal (image signal) by the image reading unit B.

  FIG. 9 shows a block diagram of an example of image processing. In the figure, the image signal output from the full color sensor 21c is input to the analog signal processing unit 71 and the gain and offset are adjusted, and then, for example, 8 bits ( 0 to 255 levels (256 gradations) of RGB digital signals, and the shading correction unit 73 uses a signal obtained by reading a reference white plate (not shown) for each color, and the sensor cell group of CCDs arranged in a line. In order to eliminate each sensitivity variation, a known shading correction is performed by optimizing the gain corresponding to each CCD sensor cell.

  The line delay unit 74 corrects a spatial shift included in the image signal output from the shading correction unit 73. This spatial shift is caused by the line sensors of the full color sensor 21c being arranged at a predetermined distance from each other in the sub-scanning direction. Specifically, the R (red) and G (green) color component signals are line-delayed in the sub-scanning direction with the B (blue) color component signal as a reference, and the phases of the three color component signals are synchronized.

The input masking unit 75 converts the color space of the image signal output from the line delay unit 74 into an NTSC standard color space by matrix calculation. That is, the full color sensor 21
The color space of each color component signal output from c is determined by the spectral characteristics of the filter of each color component, but this is converted to the NTSC standard color space.

  The LOG conversion unit 76 is configured by a look-up table (LUT) including, for example, a ROM, and converts the RGB luminance signal output from the input masking unit 75 into a CMY density signal.

  The line delay memory 77 receives the image signal output from the LOG conversion unit 76 for a period (line delay) in which a black character determination unit (not shown) generates the control signals UCR, FILTER, SEN, and the like from the output of the input masking unit 75. Delay.

  The masking / UCR unit 78 extracts the black component signal K from the image signal output from the line delay memory 77, and further, YMCK performs a matrix operation for correcting the color turbidity of the recording color material of the printer unit on the signal. For example, an 8-bit color component image signal is output in the order of M, C, Y, and K for each reading operation of the reader unit. The matrix count used for matrix calculation is set by a CPU (not shown).

  Next, based on the obtained 8-bit color component image signal Data, processing for determining the recording rates Rn and Rt of dark dots and light dots is performed. For example, if the input gradation data Data is 100/255, the light dot recording rate Rt is determined to be 250/255, and the dark dot recording rate Rn is determined to be 40/255. The recording rate is shown as an absolute value with 255 being 100 percent.

  The γ correction unit 79 performs density correction on the image signal output from the masking / UCR unit 78 in order to match the image signal with the ideal gradation characteristics of the printer unit.

  The output filter (spatial filter processing unit) 86 performs edge enhancement or smoothing processing on the image signal output from the γ correction unit 79 in accordance with a control signal from the CPU.

  The LUT 81 is used to match the density of the original image and the density of the output image, and is composed of, for example, a RAM or the like, and its conversion table is set by the CPU.

  The pulse width modulator (PWM) 82 outputs a pulse signal having a pulse width corresponding to the level of the input image signal, and the pulse signal is input to a laser driver 83 that drives a semiconductor laser (laser light source).

  This electrophotographic apparatus is provided with a pattern generator (not shown) so that gradation patterns are registered so that a signal can be directly passed to the pulse width modulator 82.

  The exposure device 3 performs laser scanning exposure L on the surface of the photoreceptor 1 based on the image signal input from the image reading unit 21 to form an electrostatic latent image.

  When the exposure device 3 performs laser scanning exposure L on the surface of the photoreceptor 1, first, based on the image signal input from the image reading unit 21, the solid-state laser element 25 is lightened and darkened at a predetermined timing by the light emission signal generator 24 ( ON / OFF). The laser light, which is an optical signal emitted from the solid-state laser element 25, is converted into a substantially parallel light beam by the collimator lens system 26, and the photoreceptor 1 is further rotated by the rotating polygon mirror 22 that rotates at high speed in the direction of arrow c. By scanning in the direction of arrow d (longitudinal direction), a laser spot is imaged on the surface of the photoreceptor 1 by the fθ lens group 23 and the reflection mirror.

  By such laser scanning, an exposure distribution corresponding to the scan is formed on the surface of the photoconductor 1, and further, by scrolling a predetermined amount perpendicular to the surface of the photoconductor 1 for each scan, the surface of the photoconductor 1 is obtained. An exposure distribution according to the image signal is obtained.

  That is, the uniformly charged surface (for example, charged to −700 V) of the photosensitive member 1 is scanned by the rotating polygon mirror 22 that rotates at a high speed the light of the solid-state laser element 25 that emits ON / OFF light corresponding to the image signal. Thus, electrostatic latent images of respective colors corresponding to the scanning exposure pattern are sequentially formed on the surface of the photoreceptor 1.

  As shown in FIG. 2, optical density detection means using LED light sources 10a and 10b and photodiodes 11a and 11b to detect the amount of reflected light of a toner patch pattern, which will be described later, formed on the photoreceptor 1. Two optical density sensors are provided in the same thrust direction. One is a scattering type optical sensor 40a used for toner density control in the developing device 3, and the other is a regular reflection type optical density sensor 40b used for γLUT correction.

  The scattering optical sensor 40a is a type of sensor that detects the patch density by increasing or decreasing the amount of scattered light from the toner and the photoconductor, and the sensor output decreases due to the toner that scatters the projection light on the photoconductor. The patch density can be detected. By calculating this value in the main body, the degree of decrease in toner density in the developing device 6 can be recognized, and replenishment control is performed from the toner replenishment tank so as to control this constant.

  As described above, in the electrophotographic apparatus of the present invention, gradation characteristics are controlled by γLUT correction by the regular reflection type optical density sensor 40b which is a regular reflection toner density detection means.

  This control achieves image stabilization by detecting the patch pattern density on the photoreceptor 1 and correcting the LUT 81 described above. Note that 200 lpi used for the gradation image is used as the patch pattern.

  FIG. 10 shows a processing circuit for processing a signal from a specular reflection type optical density sensor 40b composed of an LED light source 10b and a photodiode 11b facing the photosensitive member 1. The regular reflection type optical density sensor 40b used in this control is the regular reflection type optical density sensor 40b of the two optical density sensors arranged at the same thrust direction position facing the photosensitive member in the present embodiment. Only the regular reflection light from 1 is detected. Since this control corrects the γLUT, the effect clearly appears at the next image formation after patch formation.

  Near-infrared light from the photoreceptor 1 incident on the specular reflection type optical density sensor 40b is converted into an electric signal by the specular reflection type optical density sensor 40b, and the electric signal is 0 to 5V by the A / D conversion circuit 41. The output voltage is converted into a digital signal of 0 to 255 level, and the toner density is grasped by the density conversion circuit 42. Then, the image density is controlled using the image density control means based on the toner density information obtained from the regular reflection toner density detection means.

  FIG. 11 shows the relationship between the output of the regular reflection type optical density sensor 40b and the image density when the toner density on the photoconductor 1 is changed stepwise by the area gradation of each color.

  The output of the specular reflection type optical density sensor 40b in a state where the toner is not attached to the photoreceptor 1 is set to 5V (that is, 255 level).

As can be seen from FIG. 11, the output of the regular reflection type optical density sensor 40b decreases as the area coverage with toner increases and the image density increases. Here, if a table 42a for converting the sensor output signal dedicated to each color into a density signal is provided, the toner density signal can be read accurately for each color.

  Also, as shown in FIG. 11, when the photosensor output value becomes smaller, the image density reacts sensitively to small fluctuations in the photosensor output value in order to gain the image density and output the image density. End up. This is particularly noticeable in the low concentration region. In this case, good toner density detection cannot be performed, and even if the image density is controlled based on such a result, it is not sufficient to obtain sufficient gradation.

  However, according to the present invention, the variation in the surface roughness of the photoconductor after endurance use can be kept small, and the variation in the photosensor output value after endurance can be reduced. If the image density is originally controlled, a good image, particularly an image having excellent gradation can be stably obtained.

  The image density control means in the present invention is intended to stably maintain the color reproducibility achieved by the control system including the reader / printer. Therefore, the state immediately after the end of the control by the control system including the reader / printer is used as the target value. Set. The target value setting flow is shown in FIG. When the control of the system including both the reader / printer is finished, a patch pattern for each color of Y, M, C, and Bk is formed on the photoreceptor 1 and detected by the regular reflection type optical density sensor 40b.

  Here, the laser output of the patch uses 128 levels in the density signal for each color. At this time, the contents of the LUT 81 and the setting of the contrast potential are obtained by a control system including a reader / printer.

  The electrostatic latent image formed on the photoreceptor 1 is reversely developed by the developing device by the developing device 4 by the two-component magnetic brush method to be visualized as a first color toner image.

  In each developing device, the developer T in which the toner particles and the magnetic carrier particles are mixed is accommodated in the developing chamber R1 and the stirring chamber R2. Further, the developer T in the developing chamber R <b> 1 is transported in the longitudinal direction of the developing sleeve 30 by the rotational driving of the transport screw 37. The developer T in the stirring chamber R <b> 2 is transported in the longitudinal direction of the developing sleeve 30 by the rotational driving of the transport screw 38. The developer conveying direction by the conveying screw 38 is opposite to that by the conveying screw 37.

  The partition wall 36 is provided with openings (not shown) on the front side and the back side that are perpendicular to the paper surface, and the developer T transported by the transport screw 37 is fed from one of the openings to the transport screw. The developer T that has been transferred to the transfer screw 38 and transferred by the transfer screw 38 is transferred to the transfer screw 37 from the other one of the openings. The toner is charged to a polarity for developing the latent image by friction with the magnetic particles.

  The developing sleeve 30 is rotationally driven in the direction of arrow e (counterclockwise), and carries and conveys the developer T mixed with toner and carrier to the developing unit C. The magnetic brush of the developer T carried on the developing sleeve 30 contacts the photosensitive member 1 that rotates in the direction of arrow a (clockwise) at the developing portion C, and the electrostatic latent image is developed at the developing portion C.

A vibration bias voltage obtained by superimposing a DC voltage on an AC voltage is applied to the developing sleeve 30 by a power source (not shown). The dark portion potential (non-exposed portion potential) and the bright portion potential (exposed portion potential) of the electrostatic latent image are located between the maximum value and the minimum value of the vibration bias potential. As a result, an alternating electric field whose direction changes alternately is formed in the developing portion C. In this alternating electric field, the toner and the carrier vibrate vigorously, and the toner adheres to the bright portion of the surface of the photoreceptor 1 corresponding to the electrostatic latent image by shaking off the electrostatic restraint on the developing sleeve 30 and the carrier.

  The difference (maximum peak voltage) between the maximum value and the minimum value of the vibration bias voltage is preferably 1 to 5 kV (for example, a rectangular wave of 2 kV), and the frequency is preferably 1 to 10 kHz. The waveform of the vibration bias voltage is not limited to a rectangular wave, and may be a sine wave, a triangular wave, or the like.

  The DC voltage component is a value between the dark part potential and the bright part potential of the electrostatic latent image, but is an absolute value and closer to the dark part potential than the minimum bright part potential. However, it is preferable for preventing fog toner from adhering to the dark potential region. For example, with respect to the dark portion potential of −700 V, it is preferable that the light portion potential is −200 V and the DC component of the developing bias is −500 V. The minimum gap between the developing sleeve 30 and the photosensitive member 1 (the minimum gap position is in the developing portion C) is preferably 0.2 to 1 mm, for example, 0.5 mm.

  Further, the amount of the developer T that is regulated by the regulation blade 33 and conveyed to the developing unit C is developed by the magnetic brush of the developer T formed by the magnetic field in the developing unit C by the developing magnetic pole S1 of the magnet roller 31. It is preferable that the height on the surface of the sleeve 30 is 1.2 to 3 times the minimum gap value between the developing sleeve 30 and the photoconductor 1 with the photoconductor 1 removed. . For example, if the minimum gap value is 500 μm (0.5 mm), it may be set to 700 μm.

  The developing magnetic pole S1 of the magnet roller 31 is disposed at a position facing the developing portion C, and a magnetic brush of developer T is formed by the developing magnetic field formed by the developing magnetic pole S1 on the developing portion C, and this magnetic brush is photosensitive. The dot distribution electrostatic latent image is developed in contact with the body 1. At this time, the toner adhering to the ears (brushes) of the magnetic carrier and the toner adhering to the sleeve surface instead of the ears are transferred to the exposed portion of the electrostatic latent image and developed.

The peak value of the strength (magnetic flux density in the direction perpendicular to the surface of the developing sleeve 30) of the developing magnetic field by the developing magnetic pole S1 on the surface of the developing sleeve 30 is 5 × 10 ⁻² T to ² × 10 ⁻¹ T. Is preferred. Further, the magnet roller 31 has N1, N2, N3, and S2 poles in addition to the developing magnetic pole S1.

  Here, a developing process for visualizing an electrostatic latent image on the surface of the photoreceptor 1 by a two-component magnetic brush method using a developing device and a circulation system of the developer T will be described.

  The developer T pumped up at the N2 pole by the rotation of the developing sleeve 30 is transported from the S2 pole to the N1 pole, and the layer thickness is regulated by the regulating blade 33 in the middle thereof to form a developer thin layer. Then, the developer T spiked in the magnetic field of the developing magnetic pole S1 develops the electrostatic latent image on the photoreceptor 1. Thereafter, the developer T on the developing sleeve 30 falls into the developing chamber R1 due to the repulsive magnetic field between the N3 pole and the N2 pole. The developer T that has fallen into the developing chamber R <b> 1 is stirred and conveyed by the conveying screw 37. Further, in such a circulation system, a new toner t corresponding to the consumed toner is dropped into the stirring chamber R2 through the supply port 35 and supplied.

  On the other hand, in synchronism with the formation of the toner image on the photosensitive member 1, a transfer material P such as paper stored in the paper feed cassette 10 is fed one by one by the paper feed roller 11 or 12, and the registration roller 13 is fed to the transfer body 5 at a predetermined timing, and the transfer material P is electrostatically attracted onto the transfer body 5 by the suction roller 14.

  The transfer material P electrostatically adsorbed on the transfer body 5 moves to a position facing the photoconductor 1 by the rotation of the transfer body 5 in the arrow direction (clockwise direction), and is transferred to the back side of the transfer material P by the transfer charger 5a. A charge having a reverse polarity to that of the toner is applied, and the toner image on the photoreceptor 1 is transferred to the surface side.

  After this transfer, the transfer residual toner remaining on the photosensitive member 1 is removed by the cleaning device 6, and then the surface of the photosensitive member 1 is further discharged by the pre-exposure lamp 7 to be used for forming the next toner image. Is done.

  Thereafter, the electrostatic latent image on the photoreceptor 1 is developed in the same manner, and the cyan toner a image, cyan toner b image, magenta toner image, yellow toner image, and black toner image formed on the photoreceptor 1 are transferred. A full color image is formed by being transferred onto the transfer material P on the transfer body 5 by the charger 5a.

  Then, the transfer material P is separated from the transfer body 5 by the separation charger 5 b, and the separated transfer material P is conveyed to the fixing device 9 through the conveyance belt 8. The transfer material P conveyed to the fixing device 9 is heated and pressed between the fixing roller 9a and the pressure roller 9b to which a small amount of oil is applied by the oil applying unit or to which no oil is applied, A full color image is fixed on the surface of the transfer material P. Thereafter, the transfer material P is discharged onto the tray 16 by the paper discharge roller 15.

  Although not shown, for example, a photosensitive member, a charging unit for charging the photosensitive member, an exposure device, a developing device, a transfer unit provided corresponding to the photosensitive member, and a plurality of cleaning devices (as many as the number of types of toner) are provided. If an electrophotographic apparatus (a so-called tandem image forming apparatus) having a conveying unit that sequentially conveys a single transfer material to a transfer position of the transfer unit and a fixing device is used, each color toner image is directly applied to the transfer material. It becomes possible to transfer, and it is possible to form an image using two or more kinds of toners without using the transfer member 5 (intermediate transfer member) described above.

  In the present invention, as an electrophotographic apparatus, a plurality of constituent elements such as the above-described photosensitive member, developing means, and cleaning means are integrally combined as an apparatus unit, and this unit is attached to the apparatus main body. You may comprise in a detachable cartridge. For example, the photosensitive member 1 and the cleaning device 6 may be integrated into one device unit, and may be detachable using a guide member such as a rail of the device body. At this time, the apparatus unit may be configured to be accompanied by a charging unit and / or a developing unit.

  The means necessary for performing a normal electrophotographic process, such as the exposure means, the developing means, and the transfer means in the present invention, are not limited at all, and the electrophotography in the cleaner-less system excluding the cleaning means due to the apparatus configuration. It is also possible to use components of the apparatus.

  The present invention is configured as an electrophotographic apparatus provided with the above photoreceptor and charging means, and is used not only for an electrophotographic copying machine but also for an electronic device such as a laser beam printer, a CRT printer, an LED printer, a liquid crystal printer, and a laser plate making. It can also be widely used in photographic application fields.

  The present invention can also be configured by a facsimile having a receiving means for receiving image information from a remote terminal.

<Example 1>
(Photoreceptor manufacturing method)

Hereinafter, “part” in the examples means “part by mass”.
The photoreceptor 1 shown in FIG. 1 of the present invention was prepared as follows.
First, the coating material for conductive layers was prepared by the following procedure. 50 parts of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of phenol resin, 20 parts of methyl cellosolve, 5 parts of methanol and silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, average 0.002 part of molecular weight 3000) was prepared by dispersing for 2 hours in a sand mill using φ1 mm glass beads. This paint was applied onto an aluminum cylinder of φ30 mm × 357.5 mm by a dip coating method and dried at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 20 μm.

  Next, 5 parts of N-methoxymethylated nylon was dissolved in 95 parts of methanol to prepare an intermediate layer coating solution. This coating solution was applied onto the conductive layer by a dip coating method and dried at 100 ° C. for 20 minutes to form an intermediate layer having a thickness of 0.6 μm.

  Next, 4 parts of hydroxygallium phthalocyanine having a strong peak at a Bragg angle (2θ ± 0.2 °) of 7.4 ° and 28.2 ° in CuKα characteristic X-ray diffraction, polyvinyl butyral (trade name: Estrek BX1, 2 parts of Sekisui Chemical Co., Ltd.) and 80 parts of cyclohexanone were dispersed for 4 hours in a sand mill using glass beads having a diameter of 1 mm, and then 80 parts of ethyl acetate was added to prepare a coating solution for charge generation layer. This coating solution was applied onto the intermediate layer by a dip coating method and dried at 100 ° C. for 15 minutes to form a charge generation layer having a thickness of 0.2 μm.

  Next, 10 parts of a charge transport material which is a styryl compound of the following formula (1) and 10 parts of polycarbonate (weight average molecular weight = 46000) are dissolved in a mixed solvent of 30 parts of dichloromethane / 60 parts of monochlorobenzene to prepare a solution. Then, this solution was dip-coated on the surface of the charge generation layer and dried at 120 ° C. for 60 minutes to form a charge transport layer having a thickness of 10 μm.

Next, 45 parts of the compound shown in Compound Example No. 11 in Table 1 was mixed with n-propyl alcohol 5
It melt | dissolved in 5 parts and created the coating material for surface protection layers. This paint is applied onto the above charge transport layer by dip coating, dried at 50 ° C. for 15 minutes, and then subjected to an acceleration voltage of 150 KV and an irradiation dose of 1.5 × 10 ⁴ Gy in an oxygen concentration 80 ppm environment. Then, an electron beam was irradiated, followed by heat treatment at 150 ° C. for 3 minutes. Further, a heat treatment at 140 ° C. for 60 minutes was performed in the atmosphere to form a surface protective layer having a thickness of 5 μm, and an electrophotographic photosensitive member was produced.
(Roughening of the photoreceptor surface)

The surface of the photoreceptor prepared as described above was roughened by the roughening means shown in FIG. 3 under the following conditions.

Polishing sheet: Product name C-2000 (Fuji Photo Film Co., Ltd.)
Polishing abrasive grains: SiC (average particle diameter: 9 μm)
Base material: Polyester film (Thickness: 75 μm)
Polishing sheet feed speed: 200 mm / sec
Photoconductor rotation speed: 25 rpm
Pressing pressure: 3 N / m ²
Rotation direction of sheet and electrophotographic photosensitive member: same direction (hereinafter, the same direction is referred to as “with” and the opposite direction is referred to as “counter”).
Backup roller has an outer diameter of 40cm
Backup roller Asker C hardness: 40
Processing time: 150 seconds

  When the density, groove width, and surface roughness of the groove on the electrophotographic photosensitive member were measured, the groove density was 420, the groove width was 10.4 μm or less, Rz was 0.62 μm, and Rmax was 0.83 μm.

  Here, a non-contact three-dimensional surface measuring machine (trade name: Micromap, manufactured by Ryoka System Co., Ltd.) was used for the measurement of the groove density. This measuring machine is a high-precision laser microscope, and can observe the surface of the photosensitive member and three-dimensionalize the in-plane roughness of the viewing surface. Below, the specific example of a measuring method is shown.

  In the above-described measuring instrument, x5 is used as the objective lens, and the surface shape observation and measurement of the photoconductor with an image range of 1.6 mm × 1.2 mm are performed. This image was processed using the particle analysis software attached to the measuring machine, and the number of grooves and the groove width were measured.

  In the present invention, the groove density was calculated by counting the number of grooves falling within the range of 0.5 μm ≦ Z ≦ 40 μm by this method.

  Further, assuming the maximum image size on the photoconductor, the measurement of a total of 12 points of 4 points in the circumferential direction in the longitudinal direction is repeated within the area, and the number of grooves and the width of the photoconductor are set to 12 points. The average value was determined.

The surface roughness was measured using a contact-type surface roughness measuring instrument (trade name: Surfcorder SE3500, manufactured by Kosaka Laboratory Ltd.), detector: R2 μm, 0.7 mN diamond needle, filter: 2CR, cut. Off value: 0.8 mm, measurement length: 2.5 mm, feed rate: 0.1 mm, J
Data of maximum surface roughness Rmax and ten-point average surface roughness Rz were processed according to IS standard 1982. The measurement points are 12 points in total of 4 points in the circumferential direction in the region where the maximum image size is formed on the photosensitive drum. The surface roughnesses Rz and Rmax of the grooves of the photosensitive drum are 12 points. The average value of points was determined.

  The photoreceptor prepared by the above method was put into the image forming apparatus shown in FIG. 1 and installed in a normal temperature and humidity environment (22 ° C., 55% RH). Next, after creating a low density toner patch on the drum and adjusting the GAIN so that the output of the regular reflection type optical density sensor in the initial state is 5 V, the endurance use of 50000 sheets is performed. The value was measured.

The results are shown in Table 3. The change in the surface condition of the electrophotographic photoreceptor visually before and after the endurance was small, and the fluctuation of the sensor output value was as small as 0.2V. The toner density was detected based on the sensor value, and the image density was controlled based on the toner density information. The obtained post-durability image had gradation characteristics in the low density portion that were equivalent to those in the initial state, and had excellent gradation stability.

<Example 2>
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that 5 parts of polytetrafluoroethylene fine particles were added and dispersed in the coating for the surface protective layer of the photoreceptor of Example 1. The evaluation results are shown in Table 3.

  The change in the surface state of the electrophotographic photoreceptor visually before and after the endurance was small, and the fluctuation of the sensor output value was as small as 0.3V. The image density was controlled based on this sensor value. The obtained image after endurance had the same gradation in the low density part as in the initial state, and was excellent in gradation stability.

<Example 3>
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 20 parts of polytetrafluoroethylene fine particles were added and dispersed in the coating material for the surface protective layer of the photosensitive member of Example 1. The evaluation results are shown in Table 3.

  The change in the surface state of the electrophotographic photoreceptor visually before and after the endurance was small, and the fluctuation of the sensor output value was as small as 0.4V. The image density was controlled based on this sensor value. The obtained image after endurance had the same gradation in the low density part as in the initial state, and was excellent in gradation stability.

<Example 4>
In the surface layer roughening treatment of Example 3, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the backup roller had an Asuka-C hardness of 20 and the pressing pressure was 11 N / m ^2. And evaluated. The evaluation results are shown in Table 3.

  The change in the surface state of the electrophotographic photoreceptor visually before and after the endurance was small, and the fluctuation of the sensor output value was as small as 0.6V. The image density was controlled based on this sensor value. The obtained image after endurance had the same gradation in the low density part as in the initial state, and was excellent in gradation stability.

<Example 5>
In the surface layer roughening treatment of Example 3, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the time for the surface roughening step was 20 minutes. The evaluation results are shown in Table 3. The change in the surface state of the electrophotographic photoreceptor visually before and after the endurance was small, and the fluctuation of the sensor output value was as small as 0.5V. The image density was controlled based on this sensor value. The obtained image after endurance had the same gradation in the low density part as in the initial state, and was excellent in gradation stability.

<Example 6>
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the rotation direction of the electrophotographic photosensitive member in the surface layer roughening treatment of Example 3 was changed to a counter. The evaluation results are shown in Table 3.

  The change in the surface state of the electrophotographic photoreceptor visually before and after the endurance was small, and the fluctuation of the sensor output value was relatively small as 0.7V. The image density was controlled based on this sensor value. The obtained post-durability image had excellent gradation stability because the gradation of the low density portion was almost the same as in the initial state.

<Example 7>
In the surface layer roughening treatment of Example 3, except that the time of the roughening step was 5 minutes,
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

  There was a slight change in the surface condition of the electrophotographic photoreceptor visually before and after the durability, and it seemed that the scratches increased. The fluctuation of the sensor output value was 0.9 V, but the image density was controlled based on this sensor value. In the obtained image after durability, the gradation of the low density portion was not greatly changed from the initial state, and there was no problem in use in terms of gradation stability.

<Example 8>
In the surface roughening treatment of Example 3, an electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the time for the surface roughening process was 2 minutes. The evaluation results are shown in Table 3.

  There was a slight change in the surface condition of the electrophotographic photoreceptor visually before and after the durability, and it seemed that the scratches increased. The fluctuation of the sensor output value was 1.0 V, but the image density was controlled based on this sensor value. In the obtained image after durability, the gradation of the low density portion was not greatly changed from the initial state, and there was no problem in use in terms of gradation stability.

<Example 9>
In the surface layer roughening treatment of Example 3, the backup roller had an outer diameter of 80 mm, a Shore A hardness of 10, and a pressure applied to the electrophotographic photosensitive member of 13.5 N / m ² . Except for this, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

  There was a slight change in the surface condition of the electrophotographic photoreceptor visually before and after the durability, and it seemed that the scratches increased. The fluctuation of the sensor output value was 0.8 V, but the image density was controlled based on this sensor value. In the obtained image after durability, the gradation of the low density portion was not greatly changed from the initial state, and there was no problem in use in terms of gradation stability.

<Example 10>
After adding an initiator to the coating for the surface protective layer of the photoreceptor of Example 1, this coating was applied on the charge transport layer by a dip coating method, followed by drying at 50 ° C. for 15 minutes without performing electron beam irradiation. Then, a heat treatment at 150 ° C. for 60 minutes was performed to form a surface protective layer having a film thickness of 5 μm to produce an electrophotographic photosensitive member.
Otherwise, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

  There was a slight change in the surface condition of the electrophotographic photoreceptor visually before and after the durability, and it seemed that the scratches increased. The fluctuation of the sensor output value was 1 V, but the image density was controlled based on this sensor value. In the obtained image after durability, the gradation of the low density portion was not greatly changed from the initial state, and there was no problem in use in terms of gradation stability.

<Comparative Example 1>
The electrophotographic photosensitive member produced in Example 1 was durable without being roughened. The evaluation results are shown in Table 3. The blade squealed from around the cleaning blade from around 5000 during the endurance, and the blade broke at 7000. When the blade was replaced, it was durable up to 50000 sheets and visually compared before and after the endurance. As a result, the surface state of the electrophotographic photosensitive member was changed and many deep scratches were observed. The fluctuation of the sensor output value after endurance was 1.8 V, and the output value was considerably small. The image density was controlled based on this sensor value. The obtained endurance image clearly lost the smoothness of the gradation pattern in the low density region.

<Comparative example 2>
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the roughening time in Example 3 was set to 50 seconds. The evaluation results are shown in Table 3.

  Using a photoconductor having a groove density of 12 on the surface of the electrophotographic photosensitive member before endurance, it was endured up to 50000 sheets and visually compared before and after the endurance. Many were seen. The fluctuation of the sensor output value after endurance was 1.4 V, and the output value was considerably small. The image density was controlled based on this sensor value. The obtained endurance image clearly lost the smoothness of the gradation pattern in the low density region.

<Comparative Example 3>
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the roughening time in Example 3 was 30 min. The evaluation results are shown in Table 3.

  Using a photoconductor with a groove density of 1100 before the endurance on the surface of the electrophotographic photoreceptor, it was durable up to 50000 sheets, and when visually compared before and after the endurance, the surface state of the electrophotographic photoreceptor was changed and deep. Many wounds were found. The fluctuation of the sensor output value after endurance was 1.9 V, and the output value was considerably small. The image density was controlled based on this sensor value. The obtained post-durability image clearly lost the smoothness of the gradation pattern in the low-density region, and was a gritty image in the very thin low-density portion.

<Comparative example 4>
In the roughening step of Example 3, the electrophotographic process was performed in the same manner as in Example 1 except that the count of the polishing sheet was # 800 (trade name: C-800, manufactured by Fuji Photo Film Co., Ltd.). Photoconductors were prepared and evaluated. The evaluation results are shown in Table 3.

  Using a photoconductor with an average groove width of 45 on the surface of the electrophotographic photosensitive member before durability, the surface of the electrophotographic photosensitive member was changed when it was durable up to 50,000 sheets and visually compared before and after the durability. Many deep wounds were observed. The fluctuation of the sensor output value after endurance was 1.2 V, and the output value was small. The image density was controlled based on this sensor value. In the obtained image after durability, the smoothness of the gradation pattern in the low density region was slightly lost.

<Comparative Example 5>
The surface protective layer of Example 3 is not provided, and the charge transport layer binder resin is polycarbonate resin (trade name: Iupilon Z150, manufactured by Mitsubishi Engineering Corp.), and the film pressure is 25 (μm). Using the photoconductor prepared as described above, an electrophotographic photoconductor was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

  When the durability was increased to 50,000 sheets, the surface state of the electrophotographic photosensitive member was greatly roughened and many deep scratches were observed. The fluctuation of the sensor output value after endurance was 2 V, and the output value was very small. The image density was controlled based on this sensor value. The obtained post-durability image clearly lost the smoothness of the gradation pattern in the low-density region, and was a gritty image in the very thin low-density portion.

It is the schematic which shows the example of the electrophotographic apparatus of this invention. It is the schematic which shows arrangement | positioning of the optical density detection means in the electrophotographic apparatus of FIG. 1 of this invention. It is the schematic which shows the example of the roughening means which performs the surface treatment of the electrophotographic photoreceptor which concerns on this invention. It is the schematic which shows the example of the roughening means which performs the surface treatment of the electrophotographic photoreceptor which concerns on this invention. It is the schematic which shows the example of the polishing sheet used for the manufacturing method of the electrophotographic photoreceptor of this invention. It is the schematic which shows the example of the exposure means of the electrophotographic apparatus of this invention. It is the schematic which shows the example of the developing means of the electrophotographic apparatus of this invention. It is the schematic which shows the example of the cleaning means which provided the brush member of the electrophotographic apparatus of this invention together. It is a block diagram which shows the example of the image processing performed with the electrophotographic apparatus of this invention. It is a flowchart which shows from the photo sensor of the electrophotographic apparatus of this invention to density | concentration conversion. It is a figure which shows the relationship between the photosensor output of the electrophotographic apparatus of this invention, and image density. It is a figure which shows the flowchart of target value setting.

Claims (1)

An electrophotographic photosensitive member which is rotationally driven, a charging unit, an exposing means and the developing means and the transfer means and positive for detecting the toner density on the electrophotographic photosensitive member after extent development Engineering by developing means In an electrophotographic apparatus, comprising: a reflected toner density detection means; and an image density control means for controlling the image density based on toner density information obtained from the regular reflection toner density detection means.
The surface layer of the electrophotographic photosensitive member contains a compound cured by polymerizing or crosslinking a compound having two or more polymerizable functional groups by electron beam irradiation ,
The surface of the electrophotographic photosensitive member is roughened by roughening means for roughening the surface of the electrophotographic photosensitive member by rotating the electrophotographic photosensitive member by constantly pressing the polishing sheet against the surface of the electrophotographic photosensitive member. , Grooves having a width of 0.5 to 40 μm are formed at a ratio of 20 to 1000 per unit area (/ mm ² ) ,
An electrophotographic apparatus, wherein a groove having a width larger than 40 m is not formed on the surface of the electrophotographic photosensitive member .

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